1. Field of the Invention
Embodiments of the present invention relate, in general, to systems and methods for vehicle image classification and particularly to extracting from an image real world dimensions of a vehicle that can thereafter be used for vehicle classification.
2. Relevant Background
In several jurisdictions traffic restrictions exist that are applied to vehicles based on the size of the vehicle or the vehicle's position on the roadway. For example, in several countries speed limits vary for each lane in a roadway and for particular types of vehicles. A passenger car may be governed by one speed limit while in the same lane a large truck may be restricted to a lower speed. It is also very common in congested areas for large vehicles to be prohibited from operating in one or more particular lanes of a roadway.
Automated traffic monitors such as camera speed enforcement devices or cameras associated with stop lights are currently incapable of differentiating between various classes of vehicles. Such devices are increasingly popular in areas in which it is either infeasible or prohibited to employ human enforcement of traffic laws. For example, several countries such as South Korea and Japan do not recommend the use of human resources for traffic enforcement citing an increased risk of injury to not only the traffic officer but to the public in general. In these jurisdictions traffic enforcement is conducted via sensors that monitor the speed of traffic at a particular location and, when a violation is detected, capture an image of the violator. Fines and penalties arrive in the violator's mail shortly thereafter.
Currently, the automated speed monitoring systems that conduct unsupervised law enforcement are triggered by a speed detection device such as sensors in the pavement, RADAR guns or Laser based speed detection devices. At present, these techniques are indiscriminate in their application. Thus, while this type of system works well for simple enforcement of a maximum speed limit, it fails to address variable speed restrictions or other ordinances based on vehicle classification. For example, a truck traveling over the posted speed limit for a large vehicle would not trigger a violation as long as it remained below the maximum speed for another, presumably smaller vehicle. Similarly, a commercial truck violating a lane restriction ordinance would go undetected by current monitoring devices as long as the truck's speed remained below the trigger speed for that lane.